764 
Notes. 
is less pronounced. In -S’, ociosporus two cells, the products of 
a single mother-cell, fuse, usually completely, so as to reproduce 
practically the mother-cell, spore-formation then occurring. In 
occasional cases, however, the mother-cell does not divide into two 
daughter- cel Is which fuse again, but proceeds at once to the formation 
of spores. Such cases would represent a still further suppression of 
the individuality of the conjugating cells, if it be shown that a nuclear 
division, followed by re-fusion of the two daughter-nuclei, does occur 
previous to spore-formation, the two nuclei representing the two 
daughter-cells of the usual process. If no such process takes place, 
it may be regarded as the extreme case of reduction of the sexual 
act, the spores being produced parthenogenetically or, as it appears, 
asexually. 
There is, then, a fair amount of evidence to support the view that 
the Saccharomycetes are derived from Fungi, which possessed a com- 
plete sexual act, and that this act has suffered in most cases so great 
a reduction as to be represented merely by the fusion of the two 
nuclei in the spore mother-cell, if Janssen’s and Leblanc’s observa- 
tions be correct, or for all traces of it to have disappeared, if these 
authors be wrong. 
References. 
Barker, B. T. P., A Conjugating Yeast. Proc. Roy. Soc., vol. Ixviii, p. 345. 
Schionning, H. (’ 95 ) : Nouvelle et singuliere formation de l’ascus dans unelevure. 
Compt. rend, des Meddelels. fra Carlsb. Lab. IV. 1. 1895. 
Hoffmeister, C. (’ 00 ) : Zum Nachweis des Zellkerns bei Saccharomyces. 
Sitzungsber. d. deutsch. naturw.-med. Ver. Lotos. 1900, No. 5. 
Guilliermond, A., Recherches sur la structure de quelques champignons 
inferieurs. Compt. rend., tom. cxxxii, No. 3, p. 175. 
■ Recherches histologiques sur la sporulation des levures. 
Compt. rend., tom. cxxxii, No. 19, p. 1194. 
Recherches histologiques sur la sporulation des Schizo- 
saccharomycetes. Compt. rend., tom. cxxxiii, No. 4, p. 242. 
Wager, H. (’ 98 ): The nucleus of the yeast-plant. Ann. Bot., 1898, p. 499. 
Janssen and Leblanc, Recherches cytologiques sur la cellule de levure. La 
Cellule, tom. xiv, fasc. 1, pp. 203-243. 
Cambridge, 
B. T. P. BARKER. 
